This invention relates to assemblies for the control of fluids in aerospace applications and the like. Assemblies, fluid management systems containing such assemblies and methods using the assemblies for the control of fluids in an aircraft are provided.
The collection of liquid in industrial applications (e.g., spills, condensate, pooled fluids, etc.) can cause problems over a period of time. Liquid management problems lead to corrosion, power supply loss, added weight from retained liquid, loss in efficiency, insufficient energy usage, safety hazards, growth of mold and mildew and the like.
Current methods of liquid control focus on the prevention of liquid buildup on a surface through, for example, the use of absorbent materials, protective films and tapes, and sealants. Some products aid in the removal of liquid from a surface. For example, fluid transport products, such as those available from 3M Company of St. Paul Minn. (xe2x80x9c3Mxe2x80x9d), comprise a polyolefin substrate with a low surface energy adhesive. This tape construction provides rapid fluid removal from surfaces, fluid management for corrosion reduction, and the like.
The transport of liquid across a structured surface may be characterized as xe2x80x9cactivexe2x80x9d or xe2x80x9cpassivexe2x80x9d based upon the mechanism that causes flow of the liquid. Where liquid transport pertains to a non-spontaneous liquid flow regime wherein liquid flows, for the most part, from an external force applied to the structured surface, the liquid transport mechanism is considered xe2x80x9cactivexe2x80x9d. On the other hand, where liquid is transported spontaneously without external force, the liquid transport mechanism is considered xe2x80x9cpassivexe2x80x9d.
Active liquid transport products have been developed based upon specific applications, including absorbent pads or a liquid pervious layer combined with liquid transport devices. For example, mat products including active liquid transport and absorbent pads or liquid pervious layers are described in U.S. Pat. Nos. 5,437,651 to Todd et al. and 5,349,965 to McCarver. In each case, channels are defined on a surface of a substrate to direct liquid flow from substantially all of the area of a liquid pervious layer. These products remove liquid while having the liquid pervious layer act as a liquid adsorbing and storing layer and/or to define a liquid receiving layer. In Todd et al., a flexible backing plate is attached to an absorbent portion and a vacuum source is applied to the backing plate. The backing plate comprises a plurality of channels for suction from the vacuum source across the surface of the absorbent portion. In McCarver, a flexible pad or suction rail having a liquid permeable top surface and a liquid impermeable bottom surface is connected to a vacuum source. The suction draws liquid down into a liquid receiving chamber as it passes through the liquid pervious layer, and draws the accumulated liquid away. The liquid receiving chamber contains separation means dividing the chamber into channels for keeping the chamber from collapsing when the chamber is placed under a negative pressure.
A fluid guide device having an open structure surface for attachment to a fluid transport source is described in U.S. Pat. No. 6,080,243 to Insley et al. This reference discloses an open structured surface that defines plural channels and a slot for permitting fluid communication between a distribution manifold and at least a plurality of the channels. A fluid transport source, such as a vacuum generator, is connected to the distribution manifold.
Examples of flexible fluid transport devices that utilize both active and passive fluid transport are described in U.S. Pat. Nos. 3,520,300 to Flower, 4,747,166 to Kuntz, and 5,628,735 to Skow. Active and passive microstructured films and tapes for liquid acquisition and transport are described in pending U.S. patent application Ser. No. 09/778524 now U.S. Pat No. 6,531,206. Examples of other channeled mats for fluid removal are shown in U.S. Pat. Nos. 4,533,352 to Van Beek et al. and 4,679,590 to Hergenroeder. Examples of passive fluid transport devices having channeled fluid transport structures are described in U.S. Pat. No. 5,514,120. This reference discloses the use of a liquid management member having a microstructure-bearing hydrophilic surface, preferably in combination with a liquid permeable top sheet, a back sheet, and an absorbent core disposed between the top and back sheets. The liquid management member promotes rapid directional spreading of liquids and is in contact with the absorbent core.
While the art has provided approaches to the transport of fluids, the art has generally failed to address the use of fluid transport products, such as tapes and the like, utilizing properties afforded by specialized backings. In particular, the art has not addressed the use of fluid transport products in applications requiring fire retardant properties, conformability of the fluid transport structure, integration into fuselage assemblies, flooring structures, and the like. The art has also failed to provide fluid transport products with specialized backings that may be firmly secured to a surface but can be removed from the surface without leaving significant adhesive or foam residue on the surface after the product has been removed. The art has also not provided assemblies that will pass more stringent flame retardancy tests related to materials that are incorporated into fuselage assemblies and insulation blankets used in the aerospace business.
It may be advantageous, for example, to provide fluid transport products for use in applications where a fire retardant feature is needed or is required by applicable regulations. For example, fluid transport tapes to be used in electric or electronic applications may be exposed to electrical current or possibly to short circuits. Moreover, heat generated from the use of the associated electronic component or electrical device may further increase the risk of fire. Consequently, industry standards or regulations can require that any such products satisfy qualifying tests such as burn or flammability tests, and the like. For electrical and electronics applications, the industry standard flammability test is Underwriters Laboratories (UL 94 xe2x80x9cStandard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliancesxe2x80x9d). For rail transit and transportation applications, the industry standard is American Society for Testing and Materials ASTM E662 (xe2x80x9cTest Method for Specific Optical Density of Smoke Generated by Solid Materialsxe2x80x9d) and ASTM E162 (xe2x80x9cTest for Surface Flammability of Materials Using a Radiant Energy Sourcexe2x80x9d). For aerospace applications, fluid transport tapes may have applicability to transport moisture away from the inner structures of an aircraft. In such applications, the testing criteria for the Federal Aviation Administration F.A.R. xc2xa7 25.853 (July 1990) vertical burn test, subparagraph (a)(1)(i), relates to interior compartments occupied by crews or passengers, including interior ceiling panels, interior wall panels, partitions, galley structures, large cabinet walls, structural flooring, and materials used in the construction of stowage compartments. F.A.R. xc2xa7 25.853 (July 1990) subparagraph (a)(1)(ii) relates to seat cushions, padding, decorative and nondecorative coated fabrics, leather, trays and galley furnishings, electrical conduit, thermal and acoustical insulation and insulation covering air ducting, joint and edge covering and the like. Materials used for these applications must be self-extinguishing when tested vertically in accordance with the procedures of F.A.R. xc2xa7 25.853 (July 1990) (a)(1)(i) and (a)(1)(ii). In addition, another industry standard, for rail transit and aerospace applications, is Boeing Specification Support Standard, BSS 7239 (xe2x80x9cTest Method for Toxic Gas Generation by Materials of Combustionxe2x80x9d) which requires analysis of combustion gases and has specified concentration limits on toxic gases which include HCN, NOX, CO, HCl, HF, and SO2.
In areas of an aircraft, moisture problems may exist, created by the combination of thermal/acoustic insulation and the large temperature swings that an aircraft flight path encounters. For example, the fuselage of an aircraft generally includes a metal outer skin supported around a metal frame comprising a stringer and circumferential members. Since temperatures within the fuselage must usually be controlled in order to insure the proper environment for occupants and cargo, most fuselage shells also include some form of thermal insulation. Insulation is generally included for acoustical reasons as well. In many aircraft this insulation takes the form of fiberglass blankets supported by the stringer and circumferential members.
The fiberglass is generally encased in a film bagging material to protect the fiberglass from condensate and other fluids. Bagging materials that have been used for such a purpose include metallized polyester, plain polyester, metallized polyvinyl fluoride, and polyimide. Although the bags are constructed to prevent moisture ingress over time, there is still a significant issue with the occurrence of wet blankets that have absorbed moisture from various sources like condensate, spills, plumbing leaks and inclement weather. Wet blankets are normally removed because, if not removed, they can contribute to corrosion and fuel inefficiencies during the operation of the aircraft. Other solutions being evaluated are structures under the blankets that promote airflow around the bag to increase drying. The specific flame retardancy requirements for areas in the fuselage are described below.
In 2000, the FAA (i.e., the United States Federal Aviation Administration) issued a notice of proposed rule making detailing new test methods for thermal/acoustic insulation intended to increase in-flight fire safety and post-crash burn-through resistance of insulation materials on aircraft. Materials must meet the FAA""s new in-flight fire protection test, which is based on the American Society for Testing, and Materials test designated as ASTM E 648-97, Mar. 10, 1999. The FAA has drafted a proposed requirement that would mandate both enhanced in-flight fire resistance and post-crash burn through protection (see, e.g., Department of Transportation, Federal Aviation Administration, Improved Flammability Standards for Thermal/Acoustic Insulation Materials Used in Transport Category Airplanes; Proposed Rule, 14 CFM Part 25, et al., Federal Register, Vol. 65, No. 183, Wednesday, Sep. 20, 2000, pp. 56992-57022).
To meet the foregoing fire resistant requirements for broad use of these fluid management systems, backings for tapes and the like have been incorporated into the fluid transport films wherein the backings may be made with fire retardant agents. However, the past attempts to include an effective level of a fire retardant material in a fluid transport construction (e.g., a pressure sensitive tape) resulted in a diminished effectiveness of the fluid transport product. Consequently, fire retardant constructions have not been used to provide additional performance for fluid transport tapes in electrical or electronic applications, transportation applications, or aerospace applications. Additionally, it may also be desirable to use fluid transport products in applications where fire retardant properties may or may not be needed but where conformability and stretch release properties or the like are desirable. Products having a stretch release feature can generally be removed from a substrate in a xe2x80x9ccleanxe2x80x9d manner in that the removal of the product does not leave a visible amount of residue on the substrate.
It is desirable to provide fluid transport tapes and the like comprising a fluid transport film associated with a substrate. It is also desirable to provide such tapes with a substrate that may incorporate fire retardant material. It is also desirable to provide fluid transport tapes comprising fluid transport films associated with a foamed substrate that provides stretch release properties so that the products may be easily removed from the surfaces to which they are adhered. It is also desirable to provide a fluid transport film integrated into a panel, insulation blanket, and flooring assembly that has active and passive fluid management properties, flame retardant properties, easy removal properties, for use as an active or passive fluid management system for aircraft, automotive, transportation vehicles and devices.
In a first aspect, the present invention provides an assembly comprising:
A fluid control layer having a top side and a bottom side, the top side constructed to facilitate the evaporation or the flow of a fluid disposed thereon;
A fire retardant material having a first major surface and a second major surface, the first major surface associated with the bottom side of the fluid control layer, the fire retardant material comprising a polymer; and
An adhesive layer associated with the second major surface of the fire retardant material.
In the description of the preferred embodiment, certain terms are used in describing aspect of the invention. All such terms are intended to be interpreted in a manner consistent with their usage by those skilled in the art. For convenience, by way of example and not limitation, the following meanings are set forth:
xe2x80x9cFluid control filmxe2x80x9d (xe2x80x9cFCFxe2x80x9d) or xe2x80x9cFluid transport filmxe2x80x9d (xe2x80x9cFTFxe2x80x9d) refer to a film or sheet or layer having at least one major surface capable of manipulating, guiding, containing, spontaneously wicking, transporting or otherwise controlling a fluid.
xe2x80x9cFluid transport tapexe2x80x9d refers to a fluid control film or a fluid transport film associated with a means for affixing the film to a substrate.
xe2x80x9cMicroreplicationxe2x80x9d refers to a microscopically structured surface made by a process where the surface features retain an individual feature fidelity during manufacture.
xe2x80x9cAspect ratioxe2x80x9d is the ratio of the length of a channel to its hydraulic radius.
xe2x80x9cHydraulic radiusxe2x80x9d is the wettable cross-sectional area of a channel divided by the length of its wettable perimeter.
xe2x80x9cIntumescentxe2x80x9d or xe2x80x9cIntumescencexe2x80x9d refers to materials or properties of materials, specifically the foaming or swelling of a material when exposed to high surface temperatures or flames;
xe2x80x9cIntumescent fire retardantxe2x80x9d refers to an intumescent substance that when applied to or incorporated within a combustible material, reduces or eliminates the tendency of the material to ignite when exposed to heat or flame; and in general, when exposed to flame, the intumescent induces charring and liberates non-combustible gases to form a carbonific foam which protects the matrix, cuts off the oxygen supply, and prevents dripping. Intumescent fire retardants generally comprise an acid source, a char former, and a blowing agent.
xe2x80x9cFire retardantxe2x80x9d refers to a substance that when applied to or incorporated within a combustible material, reduces or eliminates the tendency of the material to ignite when exposed to heat or flame; and
xe2x80x9cStretch releasexe2x80x9d refers to the property of an adhesive article characterized in that, when the article is pulled and elongated from a substrate surface at a rate of 30 centimeters/minute and at an angle of 45xc2x0 or less, the article detaches from a substrate surface without leaving a significant amount of visible residue on the substrate.
xe2x80x9cCleanly removablexe2x80x9d refers to the property of an adhesive article characterized in that, when the article is pulled from a surface at a rate of no greater than 30 centimeters/minute, the article detaches from the surface of the substrate without leaving significant visible residue, excluding discoloration, on the surface.
xe2x80x9cInsulation Blanketxe2x80x9d refers to insulating material that provides thermal and acoustical insulation.
In another aspect, the invention provides a fluid management system comprising a layer of insulating material associated with the foregoing assembly.
In still another aspect, the invention provides a fluid management system for aircraft having an outer fuselage surface forming the exterior surface of the aircraft, an inner fuselage surface forming the outermost interior surface of the aircraft, the system comprising the foregoing assembly associated with the inner fuselage surface.
In another aspect, the invention provides a fluid management system for aircraft having an outer fuselage surface forming the exterior surface of the aircraft, an inner fuselage surface forming the outermost interior surface of the aircraft, and an inner compartment housed within the inner surface, the inner compartment having a compartment outer surface adjacent to the inner fuselage surface, the compartment outer surface comprising the foregoing assembly.
In still another aspect, the invention provides a method for the management of fluid within an aircraft having an outer fuselage surface forming the exterior surface of the aircraft, an inner fuselage surface forming the outermost interior surface of the aircraft, and an inner compartment housed within the inner surface, the inner compartment having a compartment outer surface adjacent to the inner fuselage surface, the method comprising: placing the foregoing assembly between the compartment outer surface and the inner fuselage surface to facilitate the evaporation or the flow of fluid. In this aspect of the invention, the assembly may be affixed or otherwise associated with the inner fuselage surface or with the compartment outer surface.
Further details of the preferred embodiment of the invention will be apparent to those skilled in the art upon consideration of the remainder of the disclosure, including the Detailed Description of the Preferred Embodiment, in conjunction with the various drawings, and the appended claims.